After I blacked out last spring, I was subjected to heart monitors, blood-pressure gauges, electrocardiograms, and echocardiograms. The solution I found was a free iPhone app.

One morning last spring, I woke up on my kitchen floor covered in blood. My head ached and my nose was bleeding profusely. This was pretty alarming for me. The last I remembered, I had been sitting at the table reading something on the Internet, when my eyesight started to go fuzzy. What happened next, I had no idea. I decided to call an ambulance. While I waited for it to arrive, I checked the last time I had accessed a Web page: one minute before the ambulance call. It seemed clearly preferable to black out for one minute, as opposed to, say, ten minutes or an hour, and I felt reassured, almost amused. Sixty seconds? That was it? In the emergency room, a doctor asked me in an offhand tone if anyone in my family had ever died suddenly and unexpectedly at a young age. Less cheerful now, I said no. Then he asked if my nose had always been crooked. Keen to circle back to the topic of sudden and unexpected death, I asserted that it had.

An X-ray soon confirmed that my nose was broken, but the rest of the diagnosis took longer. In the following months, I was subjected to heart monitors, blood-pressure gauges, electrocardiograms, and echocardiograms. The doctors were reluctant to divulge what they were looking for, but I had read online that heart conditions causing sudden blackouts could be fatal. The test results came back normal, prompting more tests, which were also normal. In the autumn, I passed out again while getting out of bed, at which point the possibility of my impending death really started to bother me. I lay awake at night listening to my pulse suspiciously, as if surveilling an enemy within.

Finally, another doctor wanted to know if I was drinking enough water. Dehydration could cause my naturally low blood pressure to fall even lower. Low enough for me to faint abruptly? She shrugged. Maybe. It was true I drank very little water, some days none at all. And this benign explanation for my blackouts had a lot of appeal for me: it was nonfatal, and it was something I could fix. I seized it for all it was worth, and arguably more.

Why wasn’t I drinking enough water? I just wasn’t thirsty, or wasn’t sure what thirst felt like. The symptoms of dehydration—dry mouth, headaches—were, on the other hand, very familiar. The cultural critic Mark Greif writes that such privations “go with a degree of discernment and class distinction.” To be driven by basic impulses implies an existence rooted in primal sensation; the discerning person has accumulated so much culture that no room is left for natural instinct. Was my dehydration a symptom of class aspiration? Was it a response to cultural messages around femininity, a subliminal wishing away of physical desire? Was there just something wrong with my brain?

It was at this point that I discovered an app called WaterMinder. Its function was simple. Every ninety minutes, it issued a notification bearing some friendly text like “Take a break with a cup of water!” If I followed this advice, I could enter the amount consumed into the app’s interface (in millilitres or fluid ounces, as preferred). A graphic illustrated the water entering a human body—I could even change her hair style to make her look more like me. By nightfall, my body was ideally filled to the brim with bright-blue liquid.

Many apps muscle in on territory that once belonged to conventional business: cabs, for example, or hotels. WaterMinder, by contrast, performs a function more traditionally fulfilled by the human brain—specifically, the hypothalamus, which regulates thirst. Is the hypothalamus ripe for disruption? It would seem so. WaterMinder has thousands of users who consistently report trouble remembering something without which they will literally die. “With such a hectic schedule I forget sometimes,” one reviewer writes.

For a few months, I used the app diligently, entering updates every time I made myself a cup of tea or drank a few mouthfuls of juice. I compared my day-to-day progress on a line graph and earned badges when I reached my daily goals. I didn’t have any further blackouts, so I stopped recording my intake but continued using the reminder notifications. More than a year has passed since the last time I fainted, and, frankly, the threat of total bodily collapse just isn’t the motivator it once was. When I hear the app’s chirpy tone emanating from the bottom of my handbag, I am no longer struck with terror. I don’t take a break with a cup of water. I have contracted out one of the essential functions of my body to a piece of software, only to find that—like my body—technology is surprisingly easy to ignore. ♦